Isolated nucleic acid molecules encoding cancer associated antigens, the antigens per se, and uses thereof

ABSTRACT

The invention relates to newly identified cancer associated antigens. It has been discovered that each of these molecules provokes antibodies when expressed by a subject. The ramifications of this observation are also part of this invention.

RELATED APPLICATIONS

This application is a continuation in part of Ser. No. 09/451,739 filed Nov. 30, 1999, U.S. Pat. No. 6,774,226 incorporated by reference in its entirety.

FIELD OF THE INVENTION

This invention relates to antigens associated with cancer, the nucleic acid molecules encoding them, as well as the uses of these.

BACKGROUND AND PRIOR ART

It is fairly well established that many pathological conditions, such as infections, cancer, autoimmune disorders, etc., are characterized by the inappropriate expression of certain molecules. These molecules thus serve as “markers” for a particular pathological or abnormal condition. Apart from their use as diagnostic “targets”, i.e., materials to be identified to diagnose these abnormal conditions, the molecules serve as reagents which can be used to generate diagnostic and/or therapeutic agents. A by no means limiting example of this is the use of cancer markers to produce antibodies specific to a particular marker. Yet another non-limiting example is the use of a peptide which complexes with an MHC molecule, to generate cytolytic T cells against abnormal cells.

Preparation of such materials, of course, presupposes a source of the reagents used to generate these. Purification from cells is one laborious, far from sure method of doing so. Another preferred method is the isolation of nucleic acid molecules which encode a particular marker, followed by the use of the isolated encoding molecule to express the desired molecule.

Two basic strategies have been employed for the detection of such antigens, in e.g., human tumors. These will be referred to as the genetic approach and the biochemical approach. The genetic approach is exemplified by, e.g., dePlaen et al., Proc. Natl. Sci. USA 85: 2275 (1988), incorporated by reference. In this approach, several hundred pools of plasmids of a cDNA library obtained from a tumor are transfected into recipient cells, such as COS cells, or into antigen-negative variants of tumor cell lines which are tested for the expression of the specific antigen. The biochemical approach, exemplified by, e.g., O. Mandelboim, et al., Nature 369: 69 (1994) incorporated by reference, is based on acidic elution of peptides which have bound to MHC-class I molecules of tumor cells, followed by reversed-phase high performance liquid chromography (HPLC). Antigenic peptides are identified after they bind to empty MHC-class I molecules of mutant cell lines, defective in antigen processing, and induce specific reactions with cytotoxic T-lymphocytes. These reactions include induction of CTL proliferation, TNF release, and lysis of target cells, measurable in an MTT assay, or a ⁵¹Cr release assay.

These two approaches to the molecular definition of antigens have the following disadvantages: first, they are enormously cumbersome, time-consuming and expensive; and second, they depend on the establishment of cytotoxic T cell lines (CTLs) with predefined specificity.

The problems inherent to the two known approaches for the identification and molecular definition of antigens is best demonstrated by the fact that both methods have, so far, succeeded in defining only very few new antigens in human tumors. See, e.g., van der Bruggen et al., Science 254: 1643-1647 (1991); Brichard et al., J. Exp. Med. 178: 489-495 (1993); Coulie, et al, J. Exp. Med. 180: 35-42 (1994); Kawakami, et al., Proc. Natl. Acad. Sci. USA 91: 3515-3519 (1994).

Further, the methodologies described rely on the availability of established, permanent cell lines of the cancer type under consideration. It is very difficult to establish cell lines from certain cancer types, as is shown by, e.g., Oettgen, et al., Immunol. Allerg. Clin. North Am. 10:607-637 (1990). It is also known that some epithelial cell type cancers are poorly susceptible to CTLs in vitro, precluding routine analysis. These problems have stimulated the art to develop additional methodologies for identifying cancer associated antigens.

One key methodology is described by Sahin, et al., Proc. Natl. Acad. Sci. USA 92: 11810-11913 (1995), incorporated by reference. Also, see U.S. Pat. No. 5,698,396, and application Ser. No. 08/479,328, filed on Jun. 7, 1995 and Jan. 3, 1996, respectively. All three of these references are incorporated by reference. To summarize, the method involves the expression of cDNA libraries in a prokaryotic host. (The libraries are secured from a tumor sample). The expressed libraries are then immunoscreened with absorbed and diluted sera, in order to detect those antigens which elicit high titer humoral responses. This methodology is known as the SEREX method (“Serological identification of antigens by Recombinant Expression Cloning”). The methodology has been employed to confirm expression of previously identified tumor associated antigens, as well as to detect new ones. See the above referenced patent applications and Sahin, et al., supra as well as Crew, et al., EMBO J 144: 2333-2340 (1995).

This methodology has been applied to a range of tumor types, including those described by Sahin et al., supra, and Pfieundschuh, supra as well as to esophageal cancer (Chen et al., Proc. Natl. Acad. Sci. USA 94: 1914-1918 (1997)); lung cancer (Güre et al., Cancer Res. 58: 1034-1041 (1998)); colon cancer (Ser. No.08/948,705 filed Oct. 10, 1997) incorporated by reference, and so forth. Among the antigens identified via SEREX are the SSX2 molecule (Sahin et al., Proc. Natl. Acad. Sci. USA 92: 11810-11813 (1995); Tureci et al., Cancer Res. 56: 4766-4772 (1996); NY-ESO-1 Chen, et al., Proc. Natl. Acad. Sci. USA 94: 1914-1918 (1997); and SCP1 (Ser. No. 08/892,705 filed Jul. 15, 1997) incorporated by reference. Analysis of SEREX identified antigens has shown overlap between SEREX defined and CTL defined antigens. MAGE-1, tyrosinase, and NY-ESO-1 have all been shown to be recognized by patient antibodies as well as CTLs, showing that humoral and cell mediated responses do act in concert.

It is clear from this summary that identification of relevant antigens via SEREX is a desirable aim. The inventors have applied this methodology and have identified several new antigens associated with cancer, as detailed in the description which follows.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS EXAMPLE 1

The SEREX methodology, as described by, e.g. Sahin, et al., Proc. Natl. Acad. Sci. USA 92: 11810-11813 (1995); Chen, et al., Proc. Natl. Acad. Sci. USA 94: 1914-1918 (1997), and U.S. Pat. No. 5,698,396, all of which are incorporated by reference. In brief, total RNA was extracted from a sample of a cutaneous metastasis of a breast cancer patient (referred to as “BR11” hereafter), using standard CsCI guanidine thiocyanate gradient methodologies. A cDNA library was then prepared, using commercially available kits designed for this purpose. Following the SEREX methodology referred to supra, this cDNA expression library was amplified, and screened with either autologous BR11 serum which had been diluted to 1:200, or with allogeneic, pooled serum, obtained from 7 different breast cancer patients, which had been diluted to 1:1000. To carry out the screen, serum samples were first diluted to 1:10, and then preabsorbed with lysates of E. coli that had been transfected with naked vector, and the serum samples were then diluted to the levels described supra. The final dilutions were incubated overnight at room temperature with nitrocellulose membranes containing phage plaques, at a density of 4-5000 plaque forming units (“pfus”) per 130 mm plate.

Nitrocellulose filters were washed, and incubated with alkline phosphatase conjugated, goat anti-human Fcγ secondary antibodies, and reactive phage plaques were visualized via incubation with 5-bromo-4-chloro-3-indolyl phosphate and nitroblue tetrazolium.

This procedure was also carried out on a normal testicular cDNA library, using a 1:200 serum dilution.

A total of 1.12×10⁶ pfus were screened in the breast cancer cDNA library, and 38 positive clones were identified. With respect to the testicular library, 4×10⁵ pfus were screened, and 28 positive clones were identified.

Additionally, 8×10⁵ pfus from the BR11 cDNA library were screened using the pooled serum described. Of these, 23 were positive.

The positive clones were subcloned, purified, and excised to forms suitable for insertion in plasmids. Following amplification of the plasmids, DNA inserts were evaluated via restriction mapping (EcoRI-XbaI), and clones which represented different cDNA inserts were sequenced using standard methodologies.

If sequences were identical to sequences found in GenBank, they were classified as known genes, while sequences which shared identity only with ESTs, or were identical to nothing in these data bases, were designated as unknown genes. Of the clones from the breast cancer library which were positive with autologous serum, 3 were unknown genes. Of the remaining 35, 15 were identical to either NY-ESO-1, or SSX2, two known members of the CT antigen family described supra, while the remaining clones corresponded to 14 known genes. Of the testicular library, 12 of the clones were SSX2.

The NY-ESO-1 antigen was not found, probably because the commercial library that was used had been size fractionated to have an average length of 1.5 kilobases, which is larger than full length NY-ESO-1 cDNA which is about 750 base pairs long.

With respect to the screening carried out with pooled, allogeneic sera, four of the clones were NY-ESO-1. No other CT antigens were identified. With the exception of NY-ESO-1, all of the genes identified were expressed universally in normal tissue.

A full listing of the isolated genes, and their frequency of occurrence follows, in tables 1, 2 and 3. Two genes were found in both the BR11 and testicular libraries, i.e., poly (ADP-ribose) polymerase, and tumor suppression gene ING1. The poly (ADP-ribose) polymerase gene has also been found in colon cancer libraries screened via SEREX, as is disclosed by Scanlan, et al., Int. J. Cancer 76: 652-58 (1998) when the genes identified in the screening of the BR11 cDNA library by autologous and allogeneic sera were compared, NY-ESO-1 and human keratin.

TABLE 1 SEREX-defined genes identified by autologous screening of BR11 cDNA library Gene No. of group clones Comments Expression CT 10  NY-ESO-1 tumor, testis genes 5 SSX2 tumor, testis Non-CT 5 Nuclear Receptor Co-Repressor ubiquitous genes 4 Poly(ADP-ribose) polymerase ubiquitous 2 Adenylosuccinatelyase ubiquitous 2 cosmid 313 (human) ESTs: muscle, brain, breast 1 CD 151 (transmembrane protein) ubiquitous 1 Human HRY Gen RT-PCR: multiple normal tissues 1 Alanyl-t-RNA-Synthetase ubiquitous 1 NAD(+) ubiquitous ADP-Ribosyltransferase 1 Human keratin 10 ESTs: multiple normal tissues 1 Human EGFR kinase substrate ubiquitous 1 ING 1 Tumor suppressor gene RT-PCR: multiple normal tissues 1 Unknown gene, ESTs: pancreas, NCI_CGAP_Pr12 liver, spleen, cDNA clone uterus 1 Unknown gene ESTs: multiple normal tissues 1 Unknown gene RT-PCR: multiple normal tissues

TABLE 2 SEREX-defined genes identified by allogeneic screening of BR11 cDNA library Gene No. of group clones Comments Expression CT 4 NY-ESO-1 tumor, testis genes Non-CT 6 zinc-finger helicase ESTs: brain, fetal genes heart, total fetus 4 Acetoacetyl-CoA-thiolase ubiquitous 3 KIAA0330 gene ESTs: multiple normal tissues 2 U1snRNP ubiquitous 1 Human aldolase A ubiquitous 1 Retinoblastoma binding protein 6 ESTs: tonsils, fetal brain, endothelial cells, brain 1 α2-Macroglobulin receptor ubiquitous associated protein 1 Human Keratin 10 ESTs: multiple normal tissues

TABLE 3 SEREX-defined genes identified by screening of a testicular cDNA library with BR11 serum Gene No. of group clones Comments Expression CT genes: 12 SSX2 tumor, testis Non-CT 3 Rho-associated coiled-coil ubiquitous genes: forming protein 3 Poly(ADP-ribose) polymerase ubiquitous 3 Gene from HeLa cell, similar to ubiquitous TTTIN 2 Gene from parathyroid tumor RT-PCR: multiple normal tissues 1 Transcription termination factor ubiquitous I-interacting peptide 21 1 Gene from fetal heart ESTs: multiple normal tissues 1 ING 1 tumor suppressor gene RT-PCR: multiple normal tissues 1 KIAA0647 cDNA ESTs: multiple normal tissues 1 KIAA0667 cDNA ESTs: multiple normal tissues

EXAMPLE 2

The mRNA expression pattern of the cDNAs identified in example 1, in both normal and malignant tissues, was studied. To do this, gene specific oligonucleotide primers were designed which would amplify cDNA segments 300-600 base pairs in length, using a primer melting temperature of 65-70° C. The primers used for amplifying MAGE-1,2,3 and 4, BAGE, NY-ESO-1, SCP1, and SSX1, 2, 3, 4 and 5 were known primers, or were based on published sequences. See Chen, et al. supra; Tureci, et al., Proc. Natl. Acad. Sci. USA 95: 5211-16(1998). Gure, et al., Int. J. Cancer 72: 965-71 (1997); Chen, et al., Proc. Natl. Acad. Sci. USA 91: 1004-1008 (1994); Gaugler, et al., J. Exp. Med. 179: 921-930 (1994), dePlaen, et al., Immunogenetics 40: 360-369 (1994), all of which are incorporated by reference. RT-PCR was carried out for 35 amplification cycles, at an annealing temperature of 60° C. Using this RT-PCR assay, the breast cancer tumor specimen was positive for a broad range of CT antigens, including MAGE-1,3 AND 4, BAGE, SSX2, NY-ESO-1 and CT7. The known CT antigens SCP-1, SSX1, 4 and 5 were not found to be expressed.

An additional set of experiments were carried out, in which the seroreactivity of patient sera against tumor antigens was tested. Specially, ELISAs were carried out, in accordance with Stockert, et al., J. Exp. Med. 187: 1349-1354(1998), incorporated by reference, to determine if antibodies were present in the patient sera. Assays were run for MAGE-1, MAGE-3, NY-ESO-1, and SSX2. The ELISAs were positive for NY-ESO-1 and SSX2, but not the two MAGE antigens.

EXAMPLE 3

Two clones (one from the breast cancer cDNA library and one from the testicular library), were identified as a gene referred to as ING1, which is a tumor suppressor gene candidate. See Garkavtsev, et al., Nature 391: 295-8 (1998), incorporated by reference. The sequence found in the breast cancer library, differed from the known sequence of ING1 at six residues, i.e., positions 818, 836, 855, 861, 866 and 874. The sequence with the six variants is set forth at SEQ ID NO: 1. The sequence of wild type ING1 is set out at SEQ ID NO: 2.

To determine if any of these differences represented a mutation in tumors, a short, PCR fragment which contained the six positions referred to supra was amplified from a panel of allogeneic normal tissue, subcloned, amplified, and sequenced following standard methods.

The results indicated that the sequences in the allogeneic tissues were identical to what was found in tumors, ruling out the hypothesis that the sequence differences were a tumor associated mutation. This conclusion was confirmed, using the testicular library clone, and using restriction analysis of ING1 cDNA taken from normal tissues. One must conclude, therefore, that the sequence information provided by Garkavtsev, et al., supra, is correct.

EXAMPLE 4

Additional experiments were carried out to determine whether genetic variations might exist in the 5′ portion of the ING1 gene, which might differ from the 5′ portion of the clone discussed supra (SEQ ID NO: 1). In a first group of experiments, attempts were made to obtain full length ING1 cDNA from both the breast tumor library, and the testicular library. SEQ ID NO: 1 was used as a probe of the library, using standard methods.

Four clones were isolated from the testicular library and none were isolated from the breast cancer library. The four clones, following sequencing, were found to derive from three transcript variants. The three variants were identical from position 586 down to their 3′ end, but differed in their 5′ regions, suggesting alternatively spliced variants, involving the same exon-intron junction. All three differed from the sequence of ING1 described by Garkavtsev, et al., in Nat. Genet.14: 415-420 (1996). These three variants are set out as SEQ ID NOS: 1, 3 and 4.

All of the sequences were then analyzed. The ORFs of SEQ ID NOS: 2, 1 and 4 (SEQ ID NO: 2 is the originally disclosed, ING1 sequence), encode polypeptides of 294, 279 and 235 amino acids, of which 233 are encoded by the 3′ region common to the three sequences. These putative sequences are set out as SEQ ID NOS:19, 5, and 7. With respect to SEQ ID NO: 3, however, no translational initiation site could be identified in its 5′ region.

EXAMPLE 5

The data regarding SEQ ID NO: 3, described supra suggested further experiments to find additional ORFs in the 5-end of variant transcripts of the molecule. In order to determine this, 5′-RACE-PCR was carried out using gene specific and adapted specific primers, together with commercially available products, and standard methodologies.

The primers used for these experiments were:

-   -   CACACAGGATCCATGTTGAGTCCTGCCAACGG     -   CGTGGTCGTGGTTGCTGGACGCG         (SEQ ID NOS: 9 and 10), for SEQ ID NO: 1;     -   CCCAGCGGCCCTGACGCTGTC     -   CGTGGTCGTGGTTGCTGGACGCG         (SEQ ID NOS: 11 and 12), for SEQ ID NO: 3; and     -   GGAAGAGATAAGGCCTAGGGAAG     -   CGTGGTCGTGGTTGCTGGACGCG         (SEQ ID NOS: 13 and 14), for SEQ ID NO: 4.

Cloning and sequencing of the products of RACE PCR showed that the variant sequence of SEQ ID NO: 4 was 5′ to SEQ ID NO: 3, and that full length cDNA for the variant SEQ ID NO: 3 contained an additional exon 609 nucleotides long, positioned between SEQ ID NO: 3 and the shared, 3′ sequence referred to supra. This exon did not include an ORF. The first available initiation site would be an initial methionine at amino acid 70 of SEQ ID NO: 1. Thus, if expressed, SEQ ID NO: 3 would correspond to a molecule with a 681 base pair, untranslated 5′ end and a region encoding 210 amino acids (SEQ ID NO:6).

EXAMPLE 6

The presence of transcript variants with at least 3 different trancriptional initiation sites, and possibly different promoters, suggested that mRNA expression might be under different, tissue specific regulation.

To determine this, variant-specific primers were synthesized, and RT-PCR was carried out on a panel of tissues, using standard methods.

SEQ ID NO: 1 was found to be expressed universally in all of the normal breast, brain and testis tissues examined, in six breast cancer lines, and 8 melanoma cell lines, and in cultured melanocytes. SEQ ID NO: 3 was found to be expressed in four of the six breast cancer lines, normal testis, liver, kidney, colon and brain. SEQ ID NO: 4 was only found to be expressed by normal testis cells and weakly in brain cells.

EXAMPLE 7

A further set of experiments were carried out to determine if antibodies against ING1 were present in sera of normal and cancer patients. A phase plaque immuno assay of the type described supra was carried out, using clones of SEQ ID NO: 1 as target Of 14 allogeneic sera taken from breast cancer patients, two were positive at 1:200 dilutions. All normal sera were negative.

EXAMPLE 8

The BR11 cDNA library described supra was then screened, using SEQ ID NO: 1 and standard methodologies. A 593 base pair cDNA was identified, which was different from any sequences in the data banks consulted. The sequence of this cDNA molecule is set out at SEQ ID NO: 8.

The cDNA molecule set forth as SEQ ID NO:1 was then used in Southern blotting experiments. In brief, genomic DNA was isolated from normal human tissue, digested with BamHI or Hind III, and then separated onto 0.7% agarose gel, blotted onto nitrocellulose filters, and hybridized using ³²p labelled SEQ ID NO: 1, at high stringency conditions (aqueous buffer, 65° C.). The probes were permitted to hybridize overnight, and then exposed for autoradiography. Two hybridizing DNA species were identified, i.e., SEQ ID NOS: 1 and 8.

EXAMPLE 9

The cDNA molecule set forth in SEQ ID NO: 8 was then analyzed. 5′-RACE PCR was carried out using normal fetus cDNA. Full length cDNA for the molecule is 771 base pairs long, without the poly A tail. It shows strong homology to SEQ ID NO: 1, with the strongest homology in the 5′ two-thirds (76% identity over nucleotide 1-480); however, the longest ORF is only 129 base pairs, and would encode a poly peptide 42 amino acids long which was homologous to, but much shorter than, the expected expression product of SEQ ID NO: 1.

In addition to the coding region, SEQ ID NO: 8 contains 203 base pairs of 5′-untranslated region, and 439 base pairs of 3 ′-untranslated region.

RT-PCR assays were carried out, as described supra. All of the normal tissues tested, including brain, colon, testis, tissue and breast, were positive for expression of this gene. Eight melanoma cell lines were tested, of which seven showed varying levels of expression, and one showed no expression. Six breast cancer cell lines were tested, of which four showed various levels of expression, and two showed no expression.

EXAMPLE 10

An additional breast cancer cDNA library, referred to as “BR17-128”, was screened, using autologous sera. A cDNA molecule was identified.

Analysis of the sequence suggested that it was incomplete at the 5′ end. To extend the sequence, a testicular cDNA library was screened with a nucleotide probe based upon the partial sequence identified in the breast cancer library. An additional 1200 base pairs were identified following these screenings. The 2011 base pairs of information are set forth in SEQ ID NO: 15.

The longest open reading frame is 1539 base pairs, corresponding to a protein of about 59.15 kilodaltons. The deduced sequence is set forth at SEQ ID NO: 16.

RT-PCR was then carried out using the following primers:

-   -   CACACAGGATCCATGCAGGCCCCGCACAAGGAG     -   CACACAAAGCTTCTAGGATTGGCACAGCCAGAG         (SEQ ID NOS: 17 and 18)

Strong signals were observed in normal testis and breast tissue, and weak expression was observed in placenta.

No expression was found in normal brain, kidney, liver, colon, adrenal, fetal brain, lung, pancreas, prostate, thymus, uterus, and ovary tissue of tumor cell lines tested, 2 of the breast cancer lines were strongly positive and two were weakly positive. Of melanoma two of 8 were strongly positive, and 3 were weakly positive. Of lung cancer cell lines, 4 of 15 were strongly positive, and 3 were weakly positive.

When cancer tissue specimens were tested, 16 of 25 breast cancer samples were strongly positive, and 3 additional samples were weakly positive. Two of 36 melanoma samples were positive (one strong, one weak). All other cancer tissue samples were negative.

When Northern blotting was carried out, a high molecular weight smear was observed in testis, but in no other tissues tested.

EXAMPLE 11

Further experiments were carried out using the tumor sample referred to in example 10, supra. This sample was derived from a subcutaneous metastasis of a 60 year old female breast cancer patient. Total RNA was extracted, as described supra. Following the extraction, a cDNA library was constructed in λ-ZAP expression vectors, also as described supra. Screening was carried out, using the protocol set forth in example 1. A total of 7×10⁵ pfus were screened. Fourteen reactive clones were identified, purified, and sequenced. The sequences were then compared to published sequences in GenBank and EST databases. These analyses indicated that the clones were derived from seven distinct genes, two of which were known, and five unknown. The two known genes were “PBK-1” (three clones), and TI-227 (one clone). These are universally expressed genes, with the libraries referred to supra showing ESTs for these genes from many different tissues.

With respect to the remaining 10 clones, six were derived from the same gene, referred to hereafter as “NY-BR-1.” Three cDNA sequences were found in the EST database which shared identity with the gene. Two of these (AI951118 and AW 373574) were identified as being derived from a breast cancer library, while the third (AW 170035), was from a pooled tissue source.

EXAMPLE 12

The distribution of the new gene NY-BR-1 referred to supra was determined via RT-PCR. In brief, gene specific oligonucleotide NY-BR-1 primers were designed to amplify cDNA segments 300-600 base pairs in length, with primer melting temperatures estimated at 65-70° C.

The RT-PCR was then carried out over 30 amplification cycles, using a thermal cycler, and an annealing temperature of 60° C. Products were analyzed via 1.5% gel electrophoresis, and ethidium bromide visualization. Fifteen normal tissues (adrenal gland, fetal brain, lung, mammary gland, pancreas, placenta, prostate, thyrnus, uterus, ovary, brain, kidney, liver, colon and testis) were assayed. The NY-BR-1 clone gave a strong signal in mammary gland and testis tissue, and a very faint signal in placenta AU other tissues were negative. The other clones were expressed universally, based upon comparison to information in the EST database library, and were not pursued further.

The expression pattern of NY-BR-1 in cancer samples was then tested, by carrying out RT-PCR, as described supra, on tumor samples.

In order to determine the expression pattern, primers:

caaagcagag cctcccgaga ag (SEQ ID NO: 20) and cctatgctgc tcttcgattc ttcc (SEQ ID NO: 21) were used. Of twenty-five breast cancer samples tested, twenty two were positive for NY-BR-1. Of these, seventeen gave strong signals, and five gave weak to modest signals.

An additional 82 non-mammary tumor samples were also analyzed, divided into 36 melanoma, 26 non small cell lung cancer, 6 colon cancer, 6 squamous cell carcinoma, 6 transitional cell carcinoma, and two leiyomyosarcomas. Only two melanoma samples were positive for NY-BR-1 expression.

The study was then extended to expression of NY-BR-1 in tissue culture. Cell lines derived from breast tumor, melanoma, and small cell lung cancer were studied. Four of six breast cancer cells were positive (two were very weak), four of eight melanoma (two very weak), and seven of fourteen small cell lung cancer lines (two very weak) were positive.

EXAMPLE 13

In order to determine the complete cDNA molecule for NY-BR-1, the sequences of the six clones referred to supra were compiled, to produce a nucleotide sequence 1464 base pairs long. Analysis of the open reading frame showed a continuous ORF throughout, indicating that the compiled sequence is not complete.

Comparison of the compiled sequence with the three EST library sequences referred to supra allowed for extension of the sequence. The EST entry AW170035 (446 base pairs long) overlapped the compiled sequence by 89 base pairs at its 5′ end, permitting extension of the sequence by another 357 base pairs. A translational terminal codon was identified in this way, leading to a molecule with a 3′-untranslated region 333 base pairs long. The 5′ end of the molecule was lacking, however, which led to the experiment described infra.

EXAMPLE 14

In order to determine the missing, 5′ end of the clone described supra, a commercially available testis cDNA expression library was screened, using a PCR expression product of the type described supra as a probe. In brief 5×104 pfus per 150 mm plate were transferred to nitrocellulose membranes, which were then submerged in denaturation solution (1.5NaCl and 0.5 M NaOH), transferred to neutralization solution (1.5 M NaCl and 0.5M Tris-HCl), and then rinsed with 0.2M Tris-HCl, and 2×SSC. Probes were labelled with ³²P and hybridization was carried out at high stringency conditions (i.e., 68° C., aqueous buffer). Any positive clones were subcloned, purified, and in vivo excised to plasmid PBK-CMV, as described supra.

One of the clones identified in this way included an additional 1346 base pairs at the 5′ end; however, it was not a full length molecule. A 5′-RACE-PCR was carried out, using commercially available products. The PCR product was cloned into plasmid vector pGEMT and sequenced. The results indicated that cDNA sequence was extended 1292 base pairs further, but no translation initiation site could be determined, because no stop codons could be detected. It could be concluded, however, that the cDNA of the NY-BR17 clone comprises at least 4026 nucleotides, which are presented as SEQ ID NO: 22. The molecule, as depicted, encodes a protein at least about 152.8 kDA in molecular weight. Structurally, there are 99 base pairs 5′ to the presumed translation initiation site, and an untranslated segment 333 base pairs long at the 3′ end. The predicted amino acid sequence of the coding region for SEQ ID NO: 22 is set out at SEQ. ID NO: 23.

SEQ ID NO: 23 was analyzed for motifs, using the known search programs PROSITE and Pfam. A bipartite nuclear localization signal motif was identified at amino acids 17-34, suggesting that the protein is a nuclear protein. Five tandem ankyrin repeats were identified, at amino acids 49-81, 82-114, 115-147, 148-180 and 181-213. A bZIP site (i.e. a DNA binding site followed by a leucine zipper motif) was found at amino acid positions 1077-1104, suggesting a transcription factor function. It was also observed that three repetitive elements were identified in between the ankyrin repeats and the bZIP DNA binding site. To elaborate, a repetitive element 117 nucleotides long is trandemly repeated 3 times, between amino acids 459-815. The second repetitive sequence, consisting of 11 amino acids, repeats 7 times between amino acids 224 and 300. The third repetitive element, 34 amino acids long, is repeated twice, between amino acids 301-368.

EXAMPLE 15

The six clones described supra were compared, and analysis revealed that they were derived from two different splice variants. Specifically, two clones, referred to as “BR17-8” and “BR 17-44a”, contain one more exon, of 111 base pairs (nucleotides 3015-3125 of SEQ ID NO: 22), which encodes amino acids 973-1009 of SEQ ID NO: 23, than do clones BR 17-1a, BR17-35b and BR17-44b. The shortest of the six clones, BR17-128, starts 3′ to the additional exons. The key structural elements referred to supra were present in both splice variants, suggesting that there was no difference in biological function.

The expression pattern of the two splice variants was assessed via PT-PCR, using primers which spanned the 111 base pair exon referred to supra.

The primers used were:

aatgggaaca agagctctgc ag (SEQ ID NO: 24) and gggtcatctg aagttcagca ttc (SEQ ID NO: 25) Both variants were expressed strongly in normal testis and breast. The longer variant was dominant in testis, and the shorter variant in breast cells. When breast cancer cells were tested, co-typing of the variant was observed, (7 strongly, 2 weakly positive, and 1 negative), with the shorter variant being the predominant form consistently.

EXAMPLE 16

The frequency of antibody response against NY-BR-1 in breast cancer patients was tested. To do this, a recombinant protein consisting of amino acids 993-1188 of SEQ ID NO: 23 was prepared. (This is the protein encoded by clone BR 17-128, referred to supra). A total of 140 serum samples were taken from breast cancer patients, as were 60 normal serum samples. These were analyzed via Western blotting, using standard methods.

Four of the cancer sera samples were positive, including a sample from patient BR 17. All normal sera were negative.

An additional set of experiments was then carried out to determine if sera recognized the portion of NY-BR-1 protein with repetitive elements. To do this, a different recombinant protein, consisting of amino acids 405-1000 was made, and tested in Western blot assays. None of the four antibody positive sera reacted with this protein indicating that an antibody epitope is located in the non-repetitive, carboxy terminal end of the molecule.

EXAMPLE 17

The screening of the testicular cDNA library referred to supra resulted, inter alia, in the identification of a cDNA molecule that was homologous to NY-BR-1. The molecule is 3673 base pairs in length, excluding the poly A tail. This corresponded to nucleotides 1-3481 of SEQ ID NO: 22, and showed 62% homology thereto. No sequence identity to sequences in libraries was noted. ORF analysis identified an ORF from nucleotide 641 through the end of the sequence, with 54% homology to the protein sequence of SEQ. ID NO: 23. The ATG initiation codon of this sequence is 292 base pairs further 3′ to the presumed initiation codon of NY-BR-1, and is preceded by 640 untranslated base pairs at its 5′ end. This 640 base pair sequence includes scattered stop codons. The nucleotide sequence and deduced amino acid sequence are presented as SEQ ID NOS: 26 and 27, respectively.

RT-PCR analysis was carried out in the same way as is described supra, using primers:

tct catagat gctggtgctg atc (SEQ ID NO: 28) and cccagacatt gaattttggc agac (SEQ ID NO: 29). Tissue restricted mRNA expression was found. The expression pattern differed from that of SEQ ID NO: 22. In brief, of six normal tissues examined, strong signals were found in brain and testis only. There was no or weak expression in normal breast tissues, and kidney, liver and colon tissues were negative. Eight of ten 10 breast cancer specimens tested supra were positive for SEQ. ID NO: 26. Six samples were positive for both SEQ. ID NO: 22 and 26, one for SEQ. ID NO: 22 only, two for the SEQ. ID NO: 26 only, and one was negative for both.

The foregoing examples describe the isolation of a nucleic acid molecule which encodes a cancer associated antigen. “Associated” is used herein because while it is clear that the relevant molecule was expressed by several types of cancer, other cancers, not screened herein, may also express the antigen.

The invention relates to nucleic acid molecules which encode the antigens encoded by, e.g., SEQ ID NOS: 1, 3, 8, 15, 22 and 26 as well as the antigens encoded thereby, such as the proteins with the amino acid sequences of SEQ ID NOS: 5, 6, 7, 16, 23 and 27. It is to be understood that all sequences which encode the recited antigen are a part of the invention.

Also a part of the invention are expression vectors which incorporate the nucleic acid molecules of the invention, in operable linkage (i.e., “operably linked”) to a promoter. Construction of such vectors, such as viral (e.g., adenovirus or Vaccinia virus) or attenuated viral vectors is well within the skill of the art, as is the transformation or transfection of cells, to produce eukaryotic cell lines, or prokaryotic cell strains which encode the molecule of interest. Exemplary of the host cells which can be employed in this fashion are COS cells, CHO cells, yeast cells, insect cells (e.g., Spodoptera frugiperda), NIH 3T3 cells, and so forth. Prokaryotic cells, such as E. coli and other bacteria may also be used. Any of these cells can also be transformed or transfected with further nucleic acid molecules, such as those encoding cytokines, e.g., interleukins such as IL-2, 4, 6, or 12 or HLA or MHC molecules.

Also a part of the invention are the antigens described herein, both in original form and in any different post translational modified forms. The molecules are large enough to be antigenic without any posttranslational modification, and hence are useful as immunogens, when combined with an adjuvant (or without it), in both precursor and post-translationally modified forms. Antibodies produced using these antigens, both poly and monoclonal, are also a part of the invention as well as hybridomas which make monoclonal antibodies to the antigens. The whole protein can be used therapeutically, or in portions, as discussed infra. Also a part of the invention are antibodies against this antigen, be these polyclonal, monoclonal, reactive fragments, such as Fab, (F(ab)₂′ and other fragments, as well as chimeras, humanized antibodies, recombinantly produced antibodies, and so forth.

As is clear from the disclosure, one may use the proteins and nucleic acid molecules of the invention diagnostically. The SEREX methodology discussed herein is premised on an immune response to a pathology associated antigen. Hence, one may assay for the relevant pathology via, e.g., testing a body fluid sample of a subject, such as serum, for reactivity with the antigen per se. Reactivity would be deemed indicative of possible presence of the pathology. So, too, could one assay for the expression of any of the antigens via any of the standard nucleic acid hybridization assays which are well known to the art, and need not be elaborated upon herein One could assay for antibodies against the subject molecules, using standard imunoassays as well.

Analysis of SEQ ID NO: 1, 3, 4, 8, 15, 22 and 26 will show that there are 5′ and 3′ non-coding regions presented therein. The invention relates to those isolated nucleic acid molecules which contain at least the coding segment, and which may contain any or all of the non-coding 5′ and 3′ portions.

Also a part of the invention are portions of the relevant nucleic acid molecules which can be used, for example, as oligonucleotide primers and/or probes, such as one or more of SEQ ID NOS: 9, 10, 11, 12, 13, 14, 17, 18,20, 21, 24, 25, 28, and 29 as well as amplification products like nucleic acid molecules comprising at least nucleotides 305-748 of SEQ ID NO: 1, or amplification products described in the examples, including those in examples 12, 14, etc.

As was discussed supra, study of other members of the “CT” family reveals that these are also processed to peptides which provoke lysis by cytolytic T cells. There has been a great deal of work on motifs for various MHC or HLA molecules, which is applicable here. Hence, a further aspect of the invention is a therapeutic method, wherein one or more peptides derived from the antigens of the invention which bind to an HLA molecule on the surface of a patient's tumor cells are administered to the patient, in an amount sufficient for the peptides to bind to the MHC/HLA molecules, and provoke lysis by T cells. Any combination of peptides may be used These peptides, which may be used alone or in combination, as well as the entire protein or immuno reactive portions thereof, may be administered to a subject in need thereof, using any of the standard types of administration, such as intravenous, intradermal, subcutaneous, oral, rectal, and transdermal administration. Standard pharmaceutical carriers, adjuvants, such as saponins, GM-CSF, and interleukins and so forth may also be used. Further, these peptides and proteins may be formulated into vaccines with the listed material, as may dendritic cells, or other cells which present relevant MHC/peptide complexes.

Similarly, the invention contemplates therapies wherein nucleic acid molecules which encode the proteins of the invention, one or more or peptides which are derived from these proteins are incorporated into a vector, such as a Vaccinia or adenovirus based vector, to render it transfectable into eukaryotic cells, such as human cells. Similarly, nucleic acid molecules which encode one or more of the peptides may be incorporated into these vectors, which are then the major constituent of nucleic acid bases therapies.

Any of these assays can also be used in progression/regression studies. One can monitor the course of abnormality involving expression of these antigens simply by monitoring levels of the protein, its expression, antibodies against it and so forth using any or all of the methods set forth supra.

It should be clear that these methodologies may also be used to track the efficacy of a therapeutic regime. Essentially, one can take a baseline value for a protein of interest using any of the assays discussed supra administer a given therapeutic agent, and then monitor levels of the protein thereafter, observing changes in antigen levels as indicia of the efficacy of the regime.

As was indicated supra, the invention involves, inter alia, the recognition of an “integrated” immune response to the molecules of the invention. One ramification of this is the ability to monitor the course of cancer therapy. In this method, which is a part of the invention, a subject in need of the therapy receives a vaccination of a type described herein. Such a vaccination results, e.g., in a T cell response against cells presenting HLA/peptide complexes on their cells. The response also includes an antibody response, possibly a result of the release of antibody provoking proteins via the lysis of cells by the T cells. Hence, one can monitor the effect of a vaccine, by monitoring an antibody response. As is indicated, supra, an increase in antibody titer may be taken as an indicia of progress with a vaccine, and vice versa Hence, a further aspect of the invention is a method for monitoring efficacy of a vaccine, following administration thereof, by determining levels of antibodies in the subject which are specific for the vaccine itself, or a large molecule of which the vaccine is a part.

The identification of the subject proteins as being implicated in pathological conditions such as cancer also suggests a number of therapeutic approaches in addition to those discussed supra. The experiments set forth supra establish that antibodies are produced in response to expression of the protein. Hence, a further embodiment of the invention is the treatment of conditions which are characterized by aberrant or abnormal levels of one or more of the proteins, via administration of antibodies, such as humanized antibodies, antibody fragments, and so forth. These may be tagged or labelled with appropriate cystostatic or cytotoxic reagents.

T cells may also be administered. It is to be noted that the T cells may be elicited in vitro using immune responsive cells such as dendritic cells, lymphocytes, or any other immune responsive cells, and then reperfused into the subject being treated.

Note that the generation of T cells and/or antibodies can also be accomplished by administering cells, preferably treated to be rendered non-proliferative, which present relevant T cell or B cell epitopes for response, such as the epitopes discussed supra.

The therapeutic approaches may also include antisense therapies, wherein an antisense molecule, preferably from 10 to 100 nucleotides in length, is administered to the subject either “neat” or in a carrier, such as a liposome, to facilitate incorporation into a cell, followed by inhibition of expression of the protein. Such antisense sequences may also be incorporated into appropriate vaccines, such as in viral vectors (e.g., Vaccinia), bacterial constructs, such as variants of the known BCG vaccine, and so forth.

Other features and applications of the invention will be clear to the skilled artisan, and need not be set forth herein. The terms and expression which have been employed are used as terms of description and not of limitation, and there is no intention in the use of such terms and expression, of excluding any aquivalents of the features shown and described or portions thereof, it being recoginized that various modifications are possible within the scope of the invention. 

1. An isolated cancer associated antigen comprising the amino acid sequence encoded by SEQ ID NO: 15, 22, or
 26. 2. The isolated cancer associated antigen of claim 1, comprising the amino acid sequence encoded by SEQ ID NO:
 15. 3. The isolated cancer associated antigen of claim 1, comprising the amino acid sequence encoded by SEQ ID NO:
 22. 4. The isolated cancer associated antigen of claim 1, comprising the amino acid sequence encoded by SEQ ID NO:
 26. 5. The isolated cancer associated antigen of claim 1, consisting of the amino acid sequence encoded by SEQ ID NO: 15, 22, or
 26. 6. An isolated cancer associated antigen comprising the amino acid sequence of SEQ ID NO: 16, 23, or
 27. 7. The isolated cancer associated antigen of claim 6, comprising the amino acid sequence of SEQ ID NO:
 16. 8. The isolated cancer associated antigen of claim 6, consisting of the amino acid sequence of SEQ ID NO:23.
 9. The isolated cancer associated antigen of claim 6, consisting of the amino acid sequence of SEQ ID NO:27.
 10. Immunogenic composition comprising the isolated cancer associated antigen of claim 1, and a pharmaceutically acceptable adjuvant.
 11. The inmunogenic composition of claim 10, wherein said adjuvant is a cytokine, a saponin or GM-CSF.
 12. Immunogenic compositions comprising the isolated cancer associated antigen of claim 6, and a pharmaceutically acceptable adjuvant.
 13. The immunogenic composition of claim 12, wherein said adjuvant is a cytokine, saponin, or GM-CSF. 